Performance Of Asphalt Mixtures Research Articles

Effects of clogging and cleaning on sound absorption performance of rubberized porous asphalt mixture

ABSTRACT The rubberized porous asphalt mixture (RPAM) has both the sound absorption capacity of air voids and the damping performance of rubber particles, which is a high-potential noise reduction pavement. However, the air voids are inevitably subjected to clogging, resulting in insufficient sound absorption performance. Moreover, it is not clear whether a large amount of rubber particles exacerbates the attenuation of sound absorption performance. Therefore, the purpose of the paper was to explore the attenuation law of sound absorption performance of RPAM under the action of multiple clogging cycles, and then optimise the preparation parameters to improve noise reduction durability. Constant head permeability test was carried out to simulate the clogging process, and manual and high-pressure washing were used to clean the clogged samples. The results showed that the attenuation process of sound absorption coefficient conformed to exponential function. The interconnected air voids were mainly clogged in the fast attenuation phase, and the open voids were clogged in the slow attenuation phase. It was more efficient to clean samples completely clogged than to clean samples clogged for three cycles. More importantly, rubber particles accelerated the attenuation of sound absorption performance during the clogging process. However, the noise reduction durability of RPAM optimised by orthogonal test was significantly improved, even better than that of porous asphalt mixture without rubber particles.

Field Performance of Asphalt Mixture Modified with Reactive Isocyanate Based Modifier

The reactive isocyanate-based modifier chemically reacts with asphalt components, overcoming the issues of increased viscosity and phase separation encountered with conventional modified binders. It can be used to modify binders to meet the highest performance grades currently specified by state highway agencies. This project aimed to demonstrate the constructability of an asphalt mixture modified with the reactive isocyanate-based modifier in the field and compare its performance with that of a control mixture. The project involved milling an approximately 5.0-cm (2-in) thick surface layer of two 30.5-m (100-foot) sections with similar foundation support. One section was resurfaced with a reactive isocyanate-modified mixture and the other with a conventional SBS-modified mix. The mixtures have shown no significant difference in field performance and laboratory performance test results. This study has provided insights into the field applicability of reactive isocyanate-based modifiers in asphalt mixtures, facilitating the ongoing efforts to develop durable road surfaces.

Towards the high RAP dosage obtained by refined processing influence on comprehensive performance of recycled asphalt mixture

The severe agglomeration of Reclaimed Asphalt Pavement (RAP) particles not only leads to high gradation variability during recycling, but also impedes the miscibility between new-old binders. This phenomenon imposes significant limitations on maximizing the utilization of RAP with high content and value. This paper first realized the effective separation of asphalt milling material by the self-developed RAP refined processing equipment to obtain coarse RAP with low binder content and fine RAP with high binder content. The fine RAP with high binder content underwent a deep rejuvenation process, and the recovery efficiency of the asphalt mortar was evaluated by CT scanning test, microscope observation test, and dynamic shear rheology test. Moreover, to investigate the strength formation characteristics of recycled asphalt mixtures with high RAP content, specific tests including wheel tracking test, three-point bending test, Hamburg Wheel Tracking test, dynamic modulus test, and two-point bending fatigue test, were conducted. By using the refined processing equipment, the asphalt film on the RAP can be precisely removed, thereby addressing the issue of aged binder agglomeration. In the coarse RAP with low binder content, the binder content was reduced to 1.48 %, allowing it to be used as a direct substitute for new aggregate, whereas the binder content of fine RAP exceeded 10 %. It was found that the direct incorporation of unrefined RAP enhanced the high-temperature stability and dynamic modulus of recycled asphalt mixture, but impacted their low-temperature cracking resistance, moisture stability, and fatigue performance. After refined processing and differentiated recycling design, the agglomeration of aged binder was reduced and the miscibility of new-old binders was improved, effectively enhancing the comprehensive performance of the recycled asphalt mixture. It should be noted that the mixing homogeneity and miscibility decrease as the RAP content exceeds 75 %, resulting in the reduction of moisture stability, cracking resistance, and fatigue performance of recycled asphalt mixture.

Influence of Basalt Fiber Morphology on the Properties of Asphalt Binders and Mixtures.

Basalt fiber (BF) has been proven to be an effective additive for improving the properties of asphalt mixtures. However, the influence of basalt fiber morphology on the properties of asphalt binders and mixtures remains inadequately explored. In this study, chopped basalt fiber (CBF) and flocculent basalt fiber (FBF) were selected to make samples for testing the influence of the two types of basalt fibers on asphalt materials. Fluorescence microscopy was used to obtain the dispersion of fiber in asphalt binders. Then, a temperature sweep test and a multiple stress creep recovery (MSCR) test were carried out to appraise the rheological characteristics of the binder. Moreover, the performance of the fiber-reinforced asphalt mixture was evaluated by a wheel tracking test, a uniaxial penetration test, an indirect tensile asphalt cracking test (IDEAL-CT), a low-temperature bending test, a water-immersion stability test, and a freeze-thaw splitting test. The results indicate that the rheological behavior of asphalt binders could be enhanced by both types of fibers. Notably, FBFs exhibit a larger contact area with asphalt mortar compared to CBFs, resulting in improved resistance to deformation under identical shear conditions. Meanwhile, the performance of the asphalt mixture underwent different levels of enhancement with the incorporation of two morphologies of basalt fiber. Specifically, as for the road property indices with FBFs, the enhancement extent of DS in the wheel tracking test, that of RT in the uniaxial penetration test, that of the CTindex in the IDEAL-CT test, and that of εB in the low-temperature trabecular bending test was 3.1%, 6.8%, 15.1%, and 6.5%, respectively, when compared to the CBF-reinforced mixtures. Compared with CBFs, FBFs significantly enhanced the elasticity and deformation recovery ability of asphalt mixtures, demonstrating greater resistance to high-temperature deformation and a more pronounced effect in delaying the onset of middle- and low-temperature cracking. Additionally, the volume of the air void for asphalt mixtures containing FBFs was lower than that containing CBFs, thereby reducing the likelihood of water damage due to excessive voids. Consequently, the moisture susceptibility enhancement of CBFs to asphalt mixture was not obvious, while FBFs could improve moisture susceptibility by more than 20%. Overall, the impact of basalt fibers with different morphologies on the properties of asphalt pavement materials varies significantly, and the research results may provide reference values for the choice of engineering fibers.

Multi-scale investigation on water stability and anti-aging performance of granite asphalt mixture modified with composite anti-stripping agents

This study aims to improve the water damage resistance of granite asphalt mixtures. Five types of composite modified asphalt were developed using organic anti-stripping agents AMRIII, LQ-2020, ultrafine hydrated lime (HL), and SBS modified asphalt, and the effects of aging on the mechanical properties of these modified asphalt mixtures were evaluated. Fourier Transform Infrared Spectroscopy (FTIR), pull-off tests, and indirect tensile strength tests were the primary analytical methods used. The results indicated that the anti-stripping agents physically mixed with the SBS modified asphalt without any chemical reaction. The SBS modified asphalt containing anti-stripping agents exhibited better mechanical strength compared to unmodified SBS asphalt, with the combined use of multiple anti-stripping agents proving more effective than individual applications. At five freeze-thaw conditions without aging, the enhancement ratios of indirect tensile strength test results of single addition of AMRIII, LQ-2020, HL and combined addition of AMRIII/HL and LQ-2020/HL were 27.27%, 36.36%, 14.29%, 50.91% and 46.41%, respectively. The addition of the anti-stripping agent enhanced the cohesive and adhesive energy. Aging reduced the water stability of the mixtures. Different modified asphalts have various sensitivity to aging, with the combination of AMRIII and HL showing the best aging resistance performance. Additionally, it was found that surface free energy had a strong correlation with water damage indicators, suggesting its potential for verifying the water stability of asphalt mixtures.

THE EFFECT OF SBR LATEX AND WARM MIX AGENT ON THE PERFORMANCE OF DRY AND WET ASPHALT MIXTURES

Moisture damage has been identified as one of the most common causes of distress in asphalt mixes. The attachment between bitumen aggregate components deteriorates when water interacts at the interface, causing the binder to be stripped from the exterior of the aggregate and cohesive breakdown inside the asphalt binder. To reduce the moisture sensitivity of asphalt mixes, styrene-butadiene rubber (SBR) and antistripping warm mix additive (WMA) have been frequently utilized. Nevertheless, the application of SBR and WMA as a compound modifier has yet to be investigated thus this research aims to evaluate the influence of SBR and WMA i.e., ZycoTherm on the moisture resistance of asphalt mixtures. For this reason, several tests, including modified Lottman, resilient modulus, and dynamic creep, were used to assess the mechanical properties of the mixes in both wet and dry situations. The results found that the SBR improved the mechanical performance of the mixture in dry conditions, whereas using the ZycoTherm as a single modifier was more effective in improving the performance of the mix in dry conditions. However, the application of the compound modifier (SBR and ZycoTherm) could optimize the performance of asphalt mixtures in both conditions i.e., dry and wet.

Study on the Characteristics of Steel Slag and its Road Performance in Asphalt Mixture

Based on the characteristics of steel slag, the application progress of steel slag as aggregate in asphalt mixture is summarized. Firstly, the differences in mechanical properties, chemical composition and physical structure of steel slag aggregates treated by different methods are summarized. The surface structure of steel slag is rough and rich in edges and corners, showing good wear resistance and crushing resistance, but there are also problems such as high density, high water absorption and volume instability. Among them, volume instability is the key factor affecting the application of steel slag in asphalt mixture. Then, the effects of steel slag aggregate on the road performance of asphalt mixture, such as water stability, rutting resistance, high temperature stability and low temperature cracking resistance, are summarized in detail. It is found that steel slag instead of coarse aggregate in asphalt mixture can improve the performance of skid resistance, rutting resistance and fatigue resistance. The water damage performance is due to the different sources of steel slag, and the uncertainty of the change results is large. On the whole, steel slag instead of aggregate can improve the road performance to a certain extent, but the volume of steel slag aggregate is unstable, which may bring some variability. In the process of road application, targeted regulation should be carried out to ensure the stability of asphalt mixture performance.

Low and intermediate temperature fracture performance of hot mix asphalt (HMA) reinforced with nano-reduced graphene oxide (NRGO) under freeze-thaw cycles and aging conditions

ABSTRACT This study evaluates the effect of nano-reduced graphene oxide (NRGO) and conditions of short- and long-term (three freeze-thaw cycles (3 FTC)) failure and six days of ageing (6 AM) on bituminous mixtures from the viewpoint of fracture toughness (KIIC and KIIIC) and fracture energy (FEII and FEIII) at ±15 °C. The results showed the fracture stiffness was improved at ±15 °C (under three conditioning states). However, the fracture flexibility was decreased and increased at low and medium temperatures, respectively. At low temperatures, the results indicated that FEIII and KIIC had the lowest resistance under unconditioned and AM conditions, while FEII and KIIC had the lowest resistance under FTC. At intermediate temperatures, FEIII and KIIC under non-conditioned and FTC conditions and FEII and KIIC under AM conditions obtained the lowest resistance. Therefore, it was recommended to check both loading states in determining the shear performance (in-plane and out-of-plane) of asphalt mixtures. Finally, by providing the minimum short- and long-term properties required to control shear and tear cracks, reinforced mixtures lead to increased service life, reduced maintenance costs and improved road safety in cold and tropical regions.

Effect of Recycled Asphalt Mixture and Solid Waste-Based Solidification Materials on Performance of Cold-Regenerated Asphalt Mixture

In this study, an aging asphalt mixture was regenerated by a waste-based rejuvenator and cemented by solid waste-based solidification materials (SSMs). A splitting test, wheel tracking test, and three-point bending test were conducted to evaluate the properties of the regenerated asphalt mixture (RAM). The results reveal that the properties of the asphalt mixture were not diminished or were moderately enhanced by the 30% substitution of RAP. With the substitution of RAP to 100%, the splitting tensile strength, dynamic stability, and splitting strength ratio were decreased by 13%, 15%, and 5%, respectively. With the 100% substitution of SSMs for cement, the compressive strength, dynamic stability, flexural strain, and splitting strength ratios of the RAM were increased by 40%, 32%%, 14%, and 8%, respectively. The lightweight components can be supplemented, and low-temperature deformation and interlayer flowability can be improved by the incorporation of the rejuvenator. The generation of hydrated calcium silicate and ettringite for SSMs is greater than those of cement. The massive generation of ettringite has been observed to increase the solid phase volume by 120%, which may facilitate a more complete filling of the remaining pores in the RAM due to water evaporation. The regeneration and cement on green and the high performance of the rejuvenator and the SSM markedly enhanced RAM performance.

Experimental Investigation and Statistical Analysis of Recycled Asphalt Pavement Mixtures Incorporating Nanomaterials

Reclaimed Asphalt Pavement (RAP) materials are used as substitutes for new materials in asphalt pavement construction, leveraging the engineering and commercial benefits of the aged binders and aggregate matrixes in RAP. These asphalt mixtures impart significant variations in volumetric properties and asphalt mixture characteristics. The current study investigates the Marshall properties, moisture susceptibility, and rutting behavior of 24 recycled asphalt mixtures developed with nanosilica and nanoclay. RAP material percent, nanomaterial content, binder grade, and extra binder were considered the factors influencing asphalt mixture performance. The above factors were analyzed using the Response Surface Methodology (RSM) to predict the Marshall and volumetric properties. Also, this investigation covers the moisture susceptibility and rut characteristics of recycled nanomaterial-modified Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA) mixes developed with Viscosity Grade 30 (VG-30) and Polymer-Modified Bitumen-40 (PMB-40). The chemical additive Zycotherm was used to develop WMA mixes. The test results indicate that adding RAP material at higher percentages and modifying the binder with nanomaterials affected moisture susceptibility with reduced moisture damage. Recycled nanosilica-modified HMA mixes developed with PMB-40 at higher RAP percentages reported higher tensile strength ratio (TSR) values in contrast with VG-30 mixes, indicating their greater susceptibility toward moisture-induced damage. The rutting potential of all of the recycled asphalt mixture combinations was enhanced by densely packed aggregate structures optimized with nanomaterials, total binder content, and RAP materials developed using the Marshall method. Overall, the nanosilica-modified recycled asphalt mixes developed with PMB40 at higher RAP percentages showed better performance in terms of strength and durability.

Effects of waste wollastonite filler on hot mix asphalt performance

Asphalt pavement plays a critical role in global infrastructure, necessitating substantial annual investments for maintenance and repair. Enhancing asphalt mixture performance is essential for prolonging pavement life and reducing associated costs. This study explores the use of waste wollastonite, a neutral mineral composed of silica and lime, as a filler material in asphalt mixtures. Comprehensive micro-scale performance tests, including Marshall Stability, resistance modulus, indirect tensile strength, and moisture sensitivity, were conducted on samples incorporating waste wollastonite. The findings indicate that replacing lime filler with waste wollastonite significantly improves asphalt performance; specifically, complete substitution resulted in increases in Marshall Stability, Marshall Quotient, and resistance modulus by 30%, 28%, and 26%, respectively. Furthermore, a 70% replacement of lime with waste wollastonite led to a 9% increase in tensile strength ratio while demonstrating a notable reduction in indirect tensile strength compared to control samples. These results suggest that waste wollastonite is a viable and effective filler option for enhancing the durability of asphalt mixtures.

Effective optimization method of asphalt binders and asphalt mixtures based on the two-parameter of contraction and relaxation

Thermal cracking is one of the primary distresses of asphalt pavement which is a complex process. Evaluating the Low-temperature Performance (LTP) of asphalt mixtures accurately and conducting material optimization analysis is not only crucial for understanding the thermal cracking mechanism of asphalt mixtures but also serve as the basis for enhancing their thermal cracking resistance performance. However, current research has not sufficiently interpreted the mechanism of thermal cracking. It is segmentary that optimizes asphalt mixtures solely based on their ultimate strength, strain, and so on at certain low-temperature points. Therefore, this study closely integrated the thermal cracking mechanism and proposed a two-parameter optimization method. Firstly, clarifying the decisive role of the contraction and relaxation relationship in determining LTP through the Thermal Stress Restrained Specimen Test (TSRST), thermal contraction test, and low-temperature relaxation test. Secondly, quantizing the impact of the aggregates skeleton and then using a two-parameter method to analyze the comprehensive effects on LTP of asphalt mixtures. Finally, summarizing the material optimization method of asphalt binder-first, aggregates-second based on the multiple linear regression method. This paper simplified the evaluation method and provided a basis for material selection and design for improving the thermal cracking resistance of asphalt mixtures.

Road Performance of Asphalt Mixture Modified with Liquid Rubber Derived from Crumb Rubber Using Olefin Metathesis

Road Performance of Asphalt Mixture Modified with Liquid Rubber Derived from Crumb Rubber Using Olefin Metathesis

Rutting and Cracking Performance of Asphalt Mixtures for 150 mm and 100 mm Diameter Samples Using Simple Performance Tests

Rutting and Cracking Performance of Asphalt Mixtures for 150 mm and 100 mm Diameter Samples Using Simple Performance Tests

Analysis of short-term self-healing performance of asphalt mixture under a three-point bending fatigue test

To evaluate the self-healing performance of asphalt mixture under repeated loads, indoor three-point bending fatigue tests and self-healing tests were conducted on asphalt mixture AC-13. The stress control mode was selected to test the fatigue resistance of the mixture, and the dissipated energy recovery value and visco-elastic ratio were proposed to evaluate the self-healing performance of the mixture. The experimental results show that there is a good linear relationship between fatigue life and fatigue stress, and the damage degree to the mixture is exponentially related to the load times. The numerical dispersion of flexural tensile modulus is large, which is not suitable for evaluating the self-healing performance of the mixture. As the number of loading cycles increases, the hysteresis dissipated energy of the mixture gradually decreases and tends to stabilize. After the loading interval, due to the self-healing effect, the visco-elastic performance of the asphalt material is partially restored. The initial dissipated energy before and after interval can be used as an evaluation index for self-healing behavior, and there is a good linear relationship between the initial dissipated energy and the damage degree. Due to the deformation migration of the mixture during the initial loading stage before and after interval, the visco-elastic ratio has changed, and this change becomes more pronounced with the damage degree of the mixture, indicating that the self-healing ability of the mixture has also been improved.

Gradation optimization of AC-20 asphalt mixture based on the fuzzy analytic hierarchy process and comprehensive evaluation method

The aggregate gradation of asphalt mixture is one of the most important factors affecting the service life of asphalt pavement. In order to study the gradation of asphalt mixture with the best comprehensive performance, this study puts forward a new method of mineral aggregate gradation optimization based on the fuzzy analytic hierarchy process and comprehensive evaluation method, aiming at the multi-level and multi-index evaluation of the road performance of asphalt mixture. First, the orthogonal test design method is applied to design nine target gradations with coarse aggregate (>4.75 mm) and fine aggregate (<4.75 mm) of AC-20 (asphalt concrete) mixture serving as two factors and the upper, middle, and lower positions of the gradation curve as three levels, and then the road performance test research is carried out. Second, a comprehensive model for evaluation of road performance of mineral aggregate gradation is established. A fuzzy complementary judgment matrix is constructed, and the index weights of each level and the hierarchical total ranking weight are calculated. Then, the membership function is introduced into the comprehensive evaluation model for the road performance of mineral aggregate gradation, and the membership values of each index of asphalt mixture road performance are obtained. Finally, the fuzzy comprehensive evaluation method is used to find out the comprehensive evaluation value of the road performance of the nine graded asphalt mixtures, and the mineral aggregate gradation is optimized. The research results show that the 1# gradation of the asphalt mixture has the highest comprehensive road performance evaluation value, and the combination of the fuzzy hierarchical analysis process and comprehensive evaluation method can more objectively and comprehensively evaluate the comprehensive road performance of the asphalt mixture and provide a useful reference for the optimal selection of asphalt mixture mineral gradation.

Performance Study of Asphalt Mixtures Reinforced with Gradated Basalt Fibers of Mixed Lengths

The length of basalt fibers affects the performance of asphalt mixtures. To explore the influence of different lengths of basalt fibers on the performance of asphalt mixtures, this study selected basalt fibers with lengths of 6 mm, 9 mm, and 12 mm to design gradations that were incorporated into asphalt mixtures to prepare specimens. High-temperature rutting tests, immersion Marshall tests, freeze-thaw splitting tests, and low-temperature splitting tests were conducted, resulting in 11 test mix designs and 12 test indicators. Then, a multi-objective grey target decision method was used to optimize the optimal combination ratio of basalt fiber lengths. The results indicate that compared to asphalt mixtures with single-length basalt fibers, incorporating well-combined basalt fibers significantly enhances the high-temperature, low-temperature, and water stability performance of asphalt mixtures. According to the grey target decision method, this study determined that a basalt fiber combination ratio of 3:4:3 for lengths of 6 mm, 9 mm, and 12 mm provides the best overall performance of asphalt mixtures. Additionally, when designing asphalt mixtures with graded basalt fibers, the inclusion of 9 mm fibers should be the primary control point. These research findings provide important guidance for the enhanced application of basalt fibers in road engineering.

The influence of Multi-Layer Plastic Packaging (MPP) on the high-temperature performance of asphalt binders and mixtures using wet and dry mixing methods

ABSTRACT High temperatures, combined with heavy traffic loads, increase the risk of permanent deformation and reduce the useful lifespan of pavements, leading to a greater need for maintenance and rehabilitation activities throughout the pavement's service life. This study aims to evaluate the effectiveness of recycled thermoplastic additives, specifically Multi-Layer Plastic Packaging (MPP) materials, in enhancing the high-temperature performance of asphalt mixtures. MPP materials, including types such as Polyester, Polyethylene, Nylon, and Metalized Polyester, were used for binder modification in asphalt mixtures. The modification was conducted using both wet and dry methods. The physical and rheological properties of the modified binders were assessed at high temperatures to determine their impact on stiffness and resistance to permanent deformation. The results indicate that MPP materials significantly improve the high-temperature performance of asphalt mixtures by enhancing binder stiffness and resistance to permanent deformation, with the wet method proving more effective than the dry method. These findings highlight the need for developing practical guidelines for incorporating MPP materials in asphalt production in the future and underscore the importance of comprehensive studies on maintenance, rehabilitation, and overall pavement lifecycle costs.

Influence of field aging on viscoelastoplastic performance of rubberized asphalt mixtures incorporating reclaimed asphalt pavement in arid urban climate

This study investigates the effects of reclaimed asphalt pavement (RAP) and crumb rubber-modified asphalt (CRMA) on the viscoelastoplastic properties of asphalt mixtures under a range of aging conditions. Six asphalt mixtures, with varying RAP contents (0 %, 30 %, and 50 %) and CRMA modifications, were evaluated through dynamic modulus (|E*|) and flow number (FN) analyses. The specimens were subjected to authentic field-aging conditions for periods of 0, 3, 6, and 9 months. The results reveal that increasing RAP content enhances volumetric properties, Marshall stability, and rutting resistance. CRMA significantly improves fatigue performance and further bolsters rutting resistance, although some detrimental effects are observed at lower temperatures. Aging has a pronounced impact on the mixtures’ performance, particularly on |E*|, Prony series coefficients, viscoelastic strain (εve), and viscoplastic strain (εvp). Newly proposed aging indices, the dynamic modulus aging index (DMAI) and viscoplastic aging index (VPAI), effectively capture the changes in viscoelastoplastic behavior under different aging durations. These findings underscore the potential of RAP and CRMA to enhance pavement durability, prolong service life, and contribute to the development of sustainable and resilient infrastructure. The research offers valuable insights into the performance of asphalt mixtures incorporating RAP and CRMA under real-world conditions.

Performance of rubber modified asphalt mixture with tire-derived aggregate subgrade

The objective of this research is to investigate the long-term performance of rubber-modified asphalt mixture (RMA) on Tire-Derived Aggregate (TDA)-replaced saturated subgrade as a drainage material. In lab testing setup, the mixtures were subjected to a 5-day conditioning at 85°C to ensure complete long-term aging. A series of laboratory and field tests were conducted. The study found that the surface course rubber mix had the best-cracking resistance than the leveling course control mix and surface layer control mix. Additionally, the fracture energy of the surface layer rubber mix was 17.4–21.9 % higher than that of the surface layer control mix. After the long-term aging condition, all three types of hot mix asphalt (HMA) exhibited exceptional resistance to deformation. Rubber-modified asphalt improved fatigue properties and crack performance. In summary, implementing RMA in pavement construction improved the pavement's thermal cracking and fatigue properties and significantly reduced pavement noise. TDA has potential as a fill material in subgrade applications, and rubber-modified asphalt shows promising performance for asphalt pavement.